Turkish President Tayyip Erdogan has agreed to forward to parliament Sweden’s bid to join the NATO military alliance, secretary-general Jens Stoltenberg says on the eve of a NATO summit in Vilnius.

“I’m glad to announce… that President Erdogan has agreed to forward the accession protocol for Sweden to the grand national assembly as soon as possible, and work closely with the assembly to ensure ratification,” Mr Stoltenberg said on Tuesday (Australian time).

Mr Stoltenberg met Erdogan and Swedish Prime Minister Ulf Kristersson ahead of the military alliance’s summit to overcome the months-long deadlock.

Mr Stoltenberg declined to give a date for when Sweden’s accession would be ratified by the Turkish parliament, the grand national assembly, which would decide on the exact timing.

Sweden and Finland applied to join NATO last year, casting aside policies of military non-alignment that had lasted through the decades of the Cold War as Russia’s invasion of Ukraine reframed security considerations.

Applications to the alliance must be approved by all NATO members and while Finland’s was given the go-ahead in April, Turkey and Hungary have held off on clearing Sweden’s bid.

Sweden has been working hard at its bid ahead of the NATO summit in Vilnius, together with the United States and its allies, urging Turkey to abandon its opposition.

Mr Erdogan has said Sweden harbours members of militant groups, mainly supporters of the Kurdistan Workers Party (PKK), who he accuses of organising demonstrations and financing terrorist groups while anti-Turkish protests in Stockholm have also raised his ire.

Meanwhile, Sweden has said it has fulfilled all the demands agreed upon in negotiations with Turkey last year, including introducing a new bill that makes being a member of a terrorist organisation illegal, and stressed freedom of speech is protected in its constitution.

Hungarian Prime Minister Viktor Orban’s chief of staff said on Thursday that Budapest would not block Sweden’s NATO membership ratification.